This project is designed to investigate movements of the articulatory structures during normal speech production to determine parameters of motor unit activity that are functionally related to the biomechanical parameters and timing characteristics of articulatory movements, and to initiate investigation of articulatory movements and motor unit activity in selected types of speech disorders. Utilizing high-speed cinefluorographic and photographic techniques and recordings of single motor units in relevant muscles, studies will be designed to determine the timing interrelationships between articulatory movements as a function of phonetic context, rate of utterance, stress and other factors and to assess such phenomena as interspike intervals, recruitment patterns, and frequency coding in articulatory muscles. Data obtained will be related to theoretical models of organization and control of the speech articulatory processes.